Name: ___________________________________________
Egg Osmosis Experiment Pre-Lab Questions (page 1)
Cells have an outer covering called the cell membrane. This membrane is selectively
permeable; it has tiny pores or holes that allow objects to move across it. The cell membrane
controls what moves in and out of the cell. Food and oxygen move into cells across the cell
membrane through the process of diffusion. Diffusion is movement of a substance from an area
of high concentration to an area of low concentration. Osmosis is a special type of diffusion; it is
the diffusion of water across a selectively permeable membrane. Osmosis occurs when water
moves from an area where it is more concentrated to an area where it is less concentrated.
In this lab you will be using an egg with the shell removed. The shell-less egg will
represent a cell and its selectively permeable membrane. You will remove the shell of the
egg by soaking the egg in vinegar. The egg shell is made up of the mineral calcium carbonate.
Calcium carbonate dissolves in acids such as vinegar. During this process it releases the gas
carbon dioxide. After the shell has been dissolved, only the membrane will remain around
the egg.
Pre-Lab questions:
1. What do you think would happen to a shell-less egg if water passed into the egg
through the membrane?
2. What do you think would happen to a shell-less egg if water passed out of the
egg through the membrane?
3. What must be able to pass through the shell and membrane in order for the
chick to develop correctly?
4. What would happen to the developing chick if the egg membrane did not
work correctly?
Name: ___________________________________________
Egg Osmosis Experiment Lab (page 2)
Materials
Tap water
metric tape
balance
Salt water
plastic containers
marker
Sugar water
4 eggs
Vinegar
Liquid of your choice
Method:
1. Place 4 chicken eggs in cups. Each egg should be in its own cup. Pour enough
vinegar to cover the egg completely but leave space at the top of the cup.
2. Allow the eggs to sit for 2 days. Gently drain the vinegar from the cup leaving
the egg in the cup. Label the cups #1, #2, #3, and #4
3. Measure each egg and record the mass and circumference in the data table.
4. Describe any other observations and draw an illustration for each egg.
5. Label each cup with a different liquid. One cup should be labeled “tap water.”
The second cup should be labeled “salt water” and the third cup should be
labeled “sugar water.” The last cup should be labeled with any liquid of your
choice.
6. Using the liquid prepared in class, fill each cup with the indicated liquid.
Supply your own liquid for the last cup (liquid of your choice).
7. Allow the cup to sit for 7 days.
8. Measure each egg and record the mass and circumference. Describe any
other observations and draw illustrations for each egg.
9. Calculate the percent mass change by ending mass x 100 divided by
beginning mass. Enter this number in the table.
Data Table:
Mass in
grams
Egg #1
Water
Before
After
Egg #2
Salt water
Before
After
Egg #3
Sugar
water
Before
Egg #4
Before
After
After
Circumference Percent Weight Change
in mm
Name: ___________________________________________
Egg Osmosis Experiment Lab (page 3)
Observations and Illustrations
Egg#1 (water)
Egg #2 (salt water)
Egg #3 (sugar water)
Egg #4 (your choice of liquid)
Lab Questions
Explain the mass and circumference changes for each egg. Use complete sentences
and the words “diffusion,” “osmosis,” and “movement of water.”